Replace pacmd calls with pactl to support Pipewire

[EgZvor]

pacmd does not work with Pipewire, use pactl where possible instead

Fixes #810

[hasB4K]

I'm pretty sure that this issue can be easily be resolved with the following:

            selected = ""
            default_sink = subprocess.check_output("pactl get-default-sink".split()).strip()
            if default_sink == self.current_sink:
                selected = self.format_selected

[hasB4K]

I have tested with a full pulseaudio and a full pipewire setup, and this patch works.

pactl get-default-sink and pacmd dump | grep set-default-sink | awk '{print $2}' (the equivalent bash command of the current code) gives the same outputs on a full pulseaudio setup.

[hasB4K]

Thank you @EgZvor for this patch! I think this should be merged (with the small patch that I provided). It works perfectly for me.